WASHINGTON — To Mona Cohen, a lifelong Philadelphia Democrat, democracy is under attack in the United States. In the midterm elections, she lists a woman’s right to abortion as one of many fleeting freedoms she voted to defend.Cohen, 68, feared the Supreme Court’s decision in June to eliminate women’s constitutional protections for abortion was only the beginning of a broader erosion of rights. So she backed Democrats in her state of Pennsylvania, where the party flipped a U.S. Senate seat and won …